The Effect of Glycerol on Molecular Mobility in Amorphous Sucrose Detected by Phosphorescence of Erythrosin B

Abstract

Luminescence from the triplet probe erythrosin B provides spectroscopic characteristics such as emission energy and lifetime that are sensitive to molecular mobility of the local solvent environment. This study investigated how variation in glycerol content influences the properties of an amorphous sucrose matrix by monitoring phosphorescence of erythrosin B over the temperature range from 5 to 100°C. Emission energy, lifetime, and red-edge excitation data revealed that glycerol affected the mobility of amorphous sucrose matrix primarily through plasticization when the mole ratio of glycerol/sucrose was above 0.27, resulting in a decrease in emission energy (ν p ), lifetime (C) and energy difference (Δν P ) with excitation at the absorption peak and red edge and an increase in the nonradiative, collisional quenching rate k TS0 . At mole ratios ≤0.27 and at temperatures below the matrix T g , glycerol exhibited an "antiplasticization" effect, as indicated by higher values of emission energy, lifetime, and energy difference and lower values of the matrix collisional quenching rate. Changes in the distribution of emission energy (emission bandwidth) and lifetime, and variation in the emission lifetime vs wavelength showed that glycerol reduced the spectral heterogeneity. These data illustrate the complex effect of a hydrogen bonding solute on the mobility of an amorphous, hydrogen bonded sugar matrix.

Influence of glycerol on the molecular mobility, oxygen permeability and microstructure of amorphous zein films

“…These changes are consistent with a decrease in the average extent (and perhaps rate) of dipolar reorientational motions (relaxations) around the excited state probe at low and an increase in the extent (and rate) of dipolar relaxations at high glycerol content. This is the expected response of this probe to antiplasticization (a decrease in matrix mobility) at low and plasticization (increase in matrix mobility) at high glycerol content (You & Ludescher, 2007).…”

Use of a Plasticizer for Physical Stability Prediction of Amorphous Solid Dispersions

“…However, there are a few potential complications. (i) The use of glycerol, at a low concentration, has been reported to exert an antiplasticizing effect in glasses, both in small molecule and in a polymer (maltodextrin and sucrose). , In such cases, this approach will not be effective. However, our preliminary results indicate that addition of glycerol accelerated crystallization of glassy KTZ and COX (Supporting Information; Figure S4).…”

Scaling relations in rheology of concentrated starches and maltodextrins

“…Other studies also found scaling of rheological parameters with T g /T as the zero shear viscosity of honeys (Andraca et al, 2013), but found a linear scaling of log(a T ) with (T g /T) 2 in the range 0.5 < (T g /T) 2 < 0.8. Structural relaxation in sucrose/glycerol is shown to scale with T g /T, with a leveling off in the range of T g /T > 1 (You & Ludescher, 2007). For polydisperse polyamides differing in molecular weight it is found that horizontal shift factors scale with T g /T (de Figueiredo Martins, 2019), albeit it was a non-linear relation in the range 0.85 < T g /T < 1.…”